I got them from cricketsandcicada.com They did a drop of about 250 packs last week, and they sold out in less than a day. This, was a 6 years project. I cant tell you how they compare to the Puck, potency wise. Both have a knockout stone though. Id say the Puck grows slower, is more finicky, less yield, but probably more potent. But they are also both different. Ive never smoked/grown out Puck BC2-BC3, yet, but smoked the Master Kush decades ago, and found it to be an extremely good buzz. My buddy that passed almost 2 years ago, grew out the Puck BC2, I gave him, and made seeds from it, but he passed, and the seeds were hidden, and lost. He loved the seeded stuff though. He grew it outside.
Supposed to release more Master Kush, at Speakeasy Seeds, in the near future. Ill probably get another pack. I dont know if they will have 21 seeds, in the next release.